Elevation Angle Scale on Dish

[spongella]

Often wondered how manufacturers arrive at stamping accurate elevation angle gradations on a dish. Are those markings somewhat consistent from one manufacturer to another?

How could one check if the angle stamping is accurate? Set the dish at 90 degrees (that is, dish perpendicular to the earth) using a plumb bob as a reference?

I know about those magnetic circular angle finders, but never figured where to set them on the dish.

I see from past posts that some use the sun to figure out a specific elevation angles and the dish's accuracy.

Thanks.

 

[Magic Static]

It's just a guide to get you in the ballpark. It also takes into the equation, the amount of offset the particular dish has. So the indicated angle looks weird. And you need to know if it's Elevation or Latitude being marked. Some dishes have both, one on each side.

 

[Jason S]

I'll throw this in too. Being a newbie with no dish aiming experience and a dish with no scale, I learned the hard way...

Elevation angle for 125W from dishpointer.com indicated 36.9° elevation. I tried for an extraordinary amount of time around at 36.9° to find a signal. I then found out about offset angles. The Patriot that I have is supposed to have a 27.7° offset angle. I subtracted the 27.7° dish offset from the 36.9° total angle and came up with 9.2° for the dish angle. With that knowledge, it didn't take too long for me to get my first lock... What a surprise and relief.

Anyhow, this is how I used the angle indicator on my particular dish. I believe you have a Channel Master (?), so it will differ.


This is a closeup of the angle indicator with the dish recently peaked (i.e., yesterday) for 125W. In my case, the angle indicator is a few degrees past the 9.2° calculated for my position.

Spongella, maybe this will help you some or at least give others some reference.

EDIT: I used the same angle indicator to ensure the pole was plumb (i.e., 90° N-S and E-W).

 

[spongella]

Every bit of knowledge and experience from others is valuable. Very nice pictures and explanations. Have assembled several Ku and C band dishes over the years, did not know there was an offset angle specific for an offset focus dish, just figured it was "built into" the elevation scale.

Wonder if the elevation scale mimics a standard protractor, like the ones in grade school.

Interesting mount you have there.

 

[Jason S]

For the Patriot mount in the photos, there is no elevation scale whatsoever. It's a nice sturdy mount, but nothing to indicate the elevation.

The first time I got to use a dish with an elevation scale was on a Dish dish that I converted for FTA. I thought that was such a pleasure to have an elevation and skew scale built in.

I'd say the elevation scale is much like a protractor, it displays the angle of the dish (either with or w/o the offset included). Like Magic Static said, some of the scales have the offset angle included.

 

[RimaNTSS]

Elevation scale on dish usually useless. The easiest, more proper and precise way how to adjust dish is measure leaning of the "face" of the dish. If we know elevation of the satellite and offset angle of the dish than extract smallest from biggest and final number will be necessary leaning of dish. For example: if satellite has 30* elevation and dish has 22,6* offset angle than the leaning of the dish should be 7,4*. Of course it is better to use digital protractor and metal or wooden plank to do such a measurements.

 

[Titanium]

I don't recall ever seeing a dish scale stamped on a AZ/EL mount that was not supposed to be the look angle of the dish. I agree with RimaNTSS that most scales are useless. Many scales have not been accurate, but for me these scales were only an angle estimator to get me into the ball park if I didn't know the offset angle of the reflector that I was working with. Having been on so many service calls where the self installer (or original "professional") wore out the scale markings trying to locate the satellite, I learned not to put any faith in the stamped scales. On commercial installs, we typically know the offset and simply set a straight edge on the vertical plane of the reflector to rough-in the elevation.

As a service tech, one never knows if the mast had been installed plumb or if they had dropped the dish off of the roof. I (like most techs) could tell you a thousand stories about what the bizarre things that have been found. One of my favorites was, "we were watching it yesterday and nobody touched it", but an evergreen tree obviously had been blocking the satellite for several years or the +30 skew was set to -30 degrees... Yep, watching it yesterday...